Copolymers comprising salts of nsulfoalkyl alpha, beta-unsaturated dicarboxylic imides



y 1964 T. M. LAAKSO ETAL 3,133,047

COPOLYMERS COMPRISING SALTS OF N-SULFOALKYLQR-UNSATURATED DICARBOXYLICIMIDES Original Filed Jan. 29, 1960 EMULSION ThomasMIaalcso R oberi-Fleisher IN VEN TORS' ATTORNEYS United States Patent 3,133,047COPOLYMERS COMPRISING SALTS OF N- SULFOALKYL a,fl-UNSATURATED DICAR-BOXYLIC i I Thomas M. Laakso and Robert Fleisher, Rochester, N.Y.,assignors to Eastman Kodak Company, Rochester, N.Y., a corporation ofNew Jersey Original application Jan. 29, 1960, Ser. No. 5,397, newPatent No. 3,039,870, dated June 19, 1962. Divided and this applicationMar. 1, 1962, Ser. No. 176,644 Claims. (Cl. 260-785) This inventionrelates to antistatic photographic elements comprising a film or papersupport material having at least one layer thereon which contains analkali metal or ammonium salt of a copolymer of a vinyl compound and anN-sulfoalkyl derivative of an a,/3-ethylenica1ly unsaturateddicarboxylic acid imide having antistatic properties.

This application is a division of our co-pending application Serial No.5,397, now Patent No. 3,039,870, filed January 29, 1960.

It is known that styrene-maleic anhydride heteropolymer can be treatedwith alkylamines to form the corresponding N-alkyl substituted imides.However, such prior art compounds are insoluble in dilute alkalinesolutions, and further, they are relatively poor conductors of staticelectricity so that they are unsuitable for antistatic purposes,especially in the photographic art where it is desirable to have aneffective antistatic coating on the support material that can be readilyremoved by alkaline developer solutions. We have found that the alkalimetal and ammonium salts of certain derived copolymers of vinylcompounds and N-sulfoalkyl derivatives of a,B-ethylenically unsaturateddicarboxylic acid imides are not only soluble in dilute aqueous alkalinesolutions, but also have the valuable property of being relatively goodelectrical conductors and highly suited as antistatic coatings onphotographic film and paper supports.

It is, accordingly, an object of the invention to provide a new class ofpolymeric compounds and alkali metal and ammonium salts thereof. Anotherobject is to provide sheet materials that are antistatic in characterand more particularly photographic films and papers that are resistantto the build up of static electricity. Another object is to provide aprocess for preparing such polymeric compounds and salts and sheetmaterials. will become apparent hereinafter.

In accordance with the invention, We prepare our polymeric salts byreacting (1) the heteropolymer of a vinyl compound having the generalformula:

and an a,[3-unsaturated dicarboxylic anhydride having the generalformula:

wherein in each instance R stands for hydrogen, methyl group or ahalogen such as chlorine or bromine and R stands for hydrogen, phenyl, ahalogen such as chlorine or bromine, OR -COR CONH -CONHR -CONR R COOROCOR etc., wherein R stands for an alkyl group of from 1-4 carbon atoms,with (2) an aminoalkanesulfonic acid containing from 24 carbon atomssuch as, for example, fi-arninomethane sul fonic acid, l-aminopropanesulfonic acid, 2-aminopropane sulfonic acid, 3-aminopropane sulfonicacid, l-aminobutane sulfonic acid, etc. until substantial conver- Otherobjects sion to the corresponding imide occurs. Advantageously, thereaction is carried out in a liquid basic type of solvent, e.g.,pyridine, aniline, etc. at a temperature of about from 50100 C. or evenhigher if desired. The imide product is then isolated by precipitatingthe reaction mixture into a nonsolvent such as diethyl ether, followedby redissolving the precipitate in water and converting it to the saltform by the addition of an aqueous alkaline solution such as sodium,potassium or lithium hydroxides or carbonates thereof or ammoniumhydroxide to a pH of approximately 8.0 or higher. The polymeric salt isthen recovered by precipitation into a relatively larger volume ofacetone and washed with fresh acetone and dried. The polymeric saltproducts obtained by the above described procedure are soluble in waterand are preferably employed in the form of their aqueous solutions forcoating antistatic layers thereof on films and paper supports usingconventional coating techniques. Water-methanol mixed solvents areespecially efiicacious in producing continuous, smooth coatings whichare free of defects, whichresist abrasionand which adhere firmly to thesupport material.

The polymeric salt products of the invention consist essentially of acopolymer of (1) a vinyl compound of the general structure:

(2) an N-sultoalkyl imide of an a e-unsaturated dicarboxylic acid of thegeneral structure:

and (3) a maleic acid derivative of the general structure:

wherein R and R are as previously defined and wherein n stands for awhole number of from 2-4 and X stands for an alkali metal atom and theammonium group NH.,. The proportions of above (1), (2) and (3) in thepolymer molecule consist essentially of approximately 50 mole percent ofthe compound of (1), from 10-5O mole percent of the compound of (2) and40() mole percent of the compound of (3). Where the imidization reactionis complete as by prolonged heating of the reaction mixturesubstantially no residual anhydride units remain in the final product.tion is incomplete, some residual anhydride units that remain areconverted in the step of alkaline solution treatment to thecorresponding dicarboxylic acid salts. However, amounts as little as 10mole percent of the N-sulfoalkyl imide salt units in the final polymericsalt polymer molecule confer antistatic properties thereto. Thepolymeric salts prepared with the heteropolymer of styrenemaleicanhydride and taurine are preferred.

The intermediate heteropolymers can be prepared by conventionalpolymerization techniques, for example, by heating a mixture ofapproximately equimolar quantities of an appropriate vinyl compound withthe a,fi-monoethylenically unsaturated dicarboxylic anhydride, in thepresence of a polymerization catalyst such as benzoyl peroxide, acetylperoxide, sodium, potassium or ammonium persulfate, etc., the polymericproducts being then separated from the reaction mixture by conventionalmeans such as precipitation into a nonsolvent and filtering,

Where the imidization reac' washing, and drying the precipitate. llfdesired, the reaction can be carried out in emulsion form in anonsolvent employing a redox type of catalyst system and an emulsifyingagent such as the salt of higher fatty acid, e.g. sodium or potassiumstearate, palmitate, etc. or a fatty alcohol sulfate, e.g. sodium orpotassium lauryl sulfate, etc. or the reaction can be carried out in asolvent such as acetone from which the heteropolymer can be separated bypouring the reaction mixture into cold water. Where a redox system isemployed, an accelerator such as an alkali metal bisulfite, e.g. sodiumbisulfite can also be used with advantage. Suitable intermediateheteropolymers include styrene-maleic anhydride heteropolymer,ethylenemaleic anhydride heteropolymer, acrylonitrile-maleic anhydrideheteropolymer, methacrylonitrile-maleic anhydride heteropolymer, vinylchloride-maleic anhydride heteropolymer, vinylidene chloride-maleicanhydride heteropolymer, acrylamide, methacrylamide, N-alkyl and N,N-dialkyl acrylamide and methacrylamide heteropolymers with maleicanhydride, vinyl alkyl ether heteropolymers with maleic anhydride, vinylalkyl ketone heteropolyrners with maleic anhydride, wherein in eachinstance above the said alkyl group contains from l-4 carbon atoms,vinyl carboxylic acid esters such as vinyl acetate, vinyl propionate orvinyl butyrate heteropolymers with maleic anhydride, the correspondingisopropenyl carbox ylic acid esters with maleic anhydride, acrylic andmethacrylic acid esters such as methyl acrylate, butyl acrylate, methylmethacrylate, etc., heteropolymers with maleic anhydride, andcorresponding heteropolymers with other a,,B-llIlSt1tUI2lIt3ddicarboxylic acid anhydrides such as chloromaleic anhydride,dichloromaleic anhydride, bromomaleic anhydride, dibromomaleicanhydride, citraconic anhydride and dimethylmaleic anhydride.

The accompanying drawing is a sectional view of a photographic elementwherein a support material 1 composed of a cellulose derivative, e.g.cellulose acetate, cellulose propionate, cellulose acetate-butyrate,cellulose nitrate, etc., a polyamide of a dibasic carboxylic acid and adiamine, e.g. nylon, a polyester of a dibasic acid and a glycol, e.g.polyethylene terephthalate, etc., polystyrene, paper and moreparticularly baryta coated paper and the like, has coated thereon apolymeric salt of the invention and on the opposite side a layer 3 of alight-sensitive material, e.g. a gelatin-silver halide emulsion layer.Although the preferred method of employing the polymeric salts of theinvention is in the form of a backing layer as shown in the drawing, thepolymeric salts can also be incorporated in the sensitive emulsion layeror used as an overcoating layer over the sensitive emulsion layer togive antistatic properties to the photographic element. However, asindicated in the drawing, application of the polymeric salts to the backof support material, ie to the side opposite that of the sensitiveemulsion layer or layers, is preferred.

The following examples will serve to illustrate further the preparationof the polymeric salts of the invention and the application of the sameto the production of lightsensitive films and paper having excellentantistatic properties.

EXAMPLE 1 Preparation of Szyrene-Maleic Anhydride Copolymer In 7500 g.of acetone, 750 g. of styrene and 750 g. of maleic anhydride, togetherwith g. benzoyl peroxide, were reflmied at 65 C. with slow stirring in aconstant temperature water bath for 24 hours. The resulting viscous dopewas slowly poured into 50 gals. of cold tap water to precipitate thewhite fibrous copolymer. This copolymer Was then washed with fourchanges of distilled water and dried at reduced pressure at 50 C. Theyield of styrene-maleic anhydride copolymer having an intrinsicviscosity of 0.63 in acetone was 1.87 kgs.

EXAMPLE 2 Sodium Salt of Styrene-N-Sulfoethylmaleimide Copolymer Ten andone-tenth grams of thoroughly dried styrenemaleic anhydridecopolymerdissolved in ml. dry pyridine and 6.25 g. taurine were heatedat 58 C. in a constant temperature bath for 7 days with occasionalshaking. The resulting mixture was leached in fresh ether.

After removal of all the pyridine in this manner, the polymer wasdissolved in 100 ml. of distilled water. The resulting solution was madealkaline to a pH of 8 with 50% sodium hydroxide solution. The sodiumsalt of the polymer was then isolated by precipitating into acetone andleaching in fresh acetone.

The yield of light buff colored product was 13.7 g. or

90% or the theoretical value.

Analysis Calculated for 014E NSNa, Found, percent percent by by weightweight The analysis indicates that the product obtained was a copolymerconsisting essentially of approximately 50 mole percent of polymerizedstyrene, 30 mole percent of the sodium salt of polymerizedN-sulfoethylmaleimide and 20 mole percent of the sodium salt ofpolymerized maleic acid (by hydrolysis of the unreacted maleicanhydride). It was soluble in water and water-methanol mixtures.

EXAMPLE 3 Sodium Salt of Ethylone-N-Sulfoethylmaleimide Copolymer Amixture of 62.5 g. (0.5 mole) of ethylene-maleic anhydride copolymer,62.5 g. (0.5 mole) of taurine and 750 ml. of pyridine was heated andstirred under anhydrous conditions for 16 hours on a steam bath. Thereaction mixture was then diluted with an equal volume of distilledwater and made alkalinewith 50% aqueous solution of sodium hydroxide.The viscous dope was precipitated into 8 volumes of acetone. Atally-like polymer obtained was redissolved in a minimum amount ofdistilled water and reprecipitated again into 8 volumes or acetone. Thefriable, buff-colored polymer was dried at room temperature underreduced pressure. The yield was 96.7% based on the weight of initialheteropolymer. Analysis indicated that the polymeric salt productconsisted essentially of approximately 50 mole percent of polymerizedethylene, 15 mole percent of the sodium salt of polymerizedN-sulfoethylmaleimide and 35 mole percent of the sodium salt of maleicacid. 5

EXAMPLE 4 This example illustrates the antistatic properties ofphotographic films coated with the polymeric salts of the invention.

'In each instance, the polymeric salt was dissolved in a water misciblesolvent mixture, for example, a mixture consisting of about'35% byweight of water and about 65% by weight of methanol and, if desired,containing also about 0.1% by weight of a wetting agent such as a fattyalcohol sulfate, saponin, etc., in a concentration of about 0.545% ofthe polymeric salt based on the:

lists the polymeric salt, the thickness of the coatings andconductivities of the coated films.

By the addition of alkali metal salts to the above coating solutions,the conductivities can be further increased. For example, in a testcontaining 0.025% by weight of lithium chloride, based on the totalweight of the solution, with a coating thickness of 2.25, the measuredconductivity was approximately x10 mho for the product of Example 2. Aparticularly advantageous feature of the antistatic coatings of theinvention is that no scum formation occurs even with exhausted developersolutions. Similar conductivity tests were also made by coating theabove solutions onto paper having a gelatino-silver halide emulsionlayer thereon. The results obtained with the paper elements were of thesame general order as those set forth for the film elements in the abovetable.

Since conductivities of the order greater than 10- mho have been foundto alleviate difficulties from static electricity generated in thenormal handling of photographic film, it will be seen from the abovetable that by use of the polymeric salts of the invention in appropriateconcentrations and solvent combinations as coatings, films can beprepared which are free from troublesome static effects.

The values for conductivity were determined by placing two parallelelectrodes on the film at a fixed relative humidity of 50%; theseelectrodes are long compared to the distance between them, so as toavoid end effects. The observed reading is divided by the distancebetween electrodes and multiplied by their length, to obtain the surfaceresistivity in ohms, the conductivity being the reciprocal thereof.

While the polymeric salts of the invention have been illustratedprimarily in connection with their use as antistatic coatings forlight-sensitive photographic films, it will be understood that coatingsthereof are also efficacious in the prevention of static build up andadhesion when coated on non-sensitized surfaces such as various naturaland synthetic wrapping materials. They also have utility for textileanti-static treatment and as dispersing or wetting agents. Also, variousfillers, dyes, softeners, gelatin, etc. can be incorporated, if desired,into the coating compositions of the invention.

What we claim is:

1. A resinous linear copolymer consisting essentially of 1)approximately 50 mole percent of a vinyl compound of the generalstructure:

(2) from 10 to '50 mole percent of an imide of the general structure:

and (3) from 40 to 0 mole percent of a dibasic acid of the generalstructure:

wherein n represents a whole number of from 2 to 4, R represents amember selected from the group consisting of a hydrogen atom, a methylgroup, a chlorine atom and a bromine atom, R represents a memberselected from the group consisting of a hydrogen atom, a phenyl group, achlorine atom, a bromine atom, OR --COR -CONH CONHR CONR R COOR and OCORwherein R represents an alkyl group of from 1 to 4 carbon atoms, and Xrepresentsa member selected from the group consisting of an alkali metalatom and ammonium group.

2. A resinous linear copolymer consisting essentially of (1)approximately 50 mole percent of styrene, (2) from 10 to 50 mole percentof N-sulfoethylmaleimide sodium salt and (3) from 40- to 0 mole percentof maleic acid sodium salt.

3. A resinous linear copolymer consisting essentially of (1)approximately 50 mole percent of ethylene, (2) from 10 to 50 molepercent of N-sultoethylmaleimide sodium salt and (3) from 40 to 10 molepercent of maleic acid sodium salt.

4. A resinous linear copolymer consisting essentially of (1)approximately 50 mole percent of styrene, (2) 30' mole percent ofN-sulfoethylmaleimide sodium salt and (3) 20 mole percent of maleic acidsodium salt.

5. A resinous linear copolymer consisting essentially of (1)approximately 50 mole percent of ethylene, (2) 15 mole percent ofN-sulfoethylmaleimide sodium salt and (3) 35 mole percent of maleic acidsodium salt.

References Cited in the file of this patent UNITED STATES PATENTS NIT EDSTATESPATENT OFFICE CERTIFICATE OF vGORRECTION Patent No. 3, 133,047 May12 1964 ThomasMe L aakso et alo It is hereby c-ertif-zh'edthat error entrequiring correctio'nend that the,

appears in the above numbered patcorrected below.

Said Letters Patent should read as Column ne 20, for "lone-'10" Signedand sealed this 17th day of November 1964.,-

(SEAL) Attest:

ERNEST W. SWIDER v EDWARD J. BRENNER Attesting Officer e Commissioner ofPatents

1. A RESINOUS LINEAR COPOLYMER CONSISTING ESSENTIALLY OF (1)APPROXIMATELY 50 MOLE PERCENT OF A VINYL COMPOUND OF THE GENERALSTRUCTURE: